Tissue engineering is a field wherein artificial tissues that can be used for medical applications are created in vivo, such as implantable organs, or in vitro, such as models for tissue functionality. Constructs which have been tissue engineered usually consist of a scaffold i.e. a porous matrix that has been seeded with cells. The properties of the matrix have a significant effect on the cell activity and functionality.
Nanofibrillar cellulose (NFC) has recently found applications in various areas, including biomedical and pharmaceutical applications as well as tissue engineering. In higher plants, cellulose is organized in morphologically complex structure consisting of β(1→4) D-glucopyranose chains. These chains are laterally bound by hydrogen bonds to form fibrils with a diameter in nanoscale, which are further organized in microfibril bundles. Furthermore, cellulose molecules are associated with other polysaccharides (hemicelluloses) and lignin in plant cell walls, resulting in even more complex morphologies. The cellulose nanoscale fibers can be released from the highly ordered structure by mechanical process and combined with other treatments, such as enzymatic pre-treatment. The cellulose nanoscale fibers can be used to form hydrogels which are a family of natural and synthetic polymers which can be used for cell culturing and tissue engineering.
An area in tissue engineering is the cell seeding process. Cells may be seeded either after or during fabrication. Additive manufacturing of biocompatible materials is a way to fabricate scaffolds for tissue engineering purposes. Additive manufacturing includes fabrication techniques that form 3D structures layer by layer. Some of said techniques are suitable for fabricating scaffolds from hydrogels. Ready-to-use alginate scaffold in well plates for cell culture, such as AlgiMatrix™ 3D Culture System (Gibco®), exists on the market.
Falange and Wu et al. (2012) disclose that stem cells have been used for wound healing and tissue repair. Sirviö et al. (2014) disclose biocomposite cellulose-alginate films produced using Ca2+ crosslinking. The use of Ca2+ only in crosslinking results in a stiff but fragile structure, wherein the cells are not able to move. Yoo et al. (2014) disclose fabrication of alginate fibers using microporous membrane based molding technique.
The existing cell culture compositions have problems such as the presence of starch which makes the composition too fragile. In addition, while some hydrogels can hold their shape after printing, they are often very soft and easily squashed when handled, which can ruin detailed structures.
Despite the ongoing research and development in the area of cell culturing and tissue engineering there is still a need for the development and use of generally acceptable methodologies in order to provide improved compositions and methods for cell culturing and tissue engineering. There is also a need for a method which enables transplanted cells to be adhered to the site they are delivered.